WASHINGTON — To some partisans, it may sound jarring: President Obama talks about how he and former rival John McCain were simpatico in 2008 while Mitt Romney fondly recalls Bill Clinton’s White House tenure.

Yet lauding the prominent elder statesmen from the opposing party has become a regular feature of the 2012 presidential race, with Romney, the presumptive Republican nominee, using Clinton to score points against Obama the same way the president seeks such an advantage by invoking McCain.